106 



Georffe Heuer. 



limits, and the lymphatic ducts follow one of two courses. In the 

 one type, the lymphatic trunk penetrates the wall of the intestine 

 immediately on reaching it, that is that portion along the mesenteric 



^ J 



Fig. 7. — Injected lymphatics in a pig embryo S cm. long to show the thoracic 

 duct and that the retroperitoneal sac is being transformed into a plexus of 

 ducts the anlage of a group of lymph nodes, x 1.3. 



attachment included between the two folds of the peritoneum, as 

 shown in Fig, 8. In the other type the lymph vessel may run in 

 the serosa a variable distance, usually not more than one quarter or 



